Influence of coexistent Hashimoto's thyroiditis on the extent of cervical lymph node dissection and prognosis in papillary thyroid carcinoma

Summary

Objective

Previous studies did not focus on the differences in the extent of cervical lymph node (LN) dissection according to coexistent Hashimoto's thyroiditis (HT) in patients with papillary thyroid carcinoma (PTC) and its clinical impact. We aimed to determine whether extensive cervical LN dissection is responsible for favorable clinical outcomes in PTC patients with HT and whether coexistence of HT itself has an independent protective effect regardless of LN status.

Design

Retrospective cohort study

Patients

1,369 patients with PTC who underwent total thyroidectomy with central compartment neck dissection.

Measurements

Metastatic LN ratio, defined as number of metastatic LNs divided by number of removed LNs, was used to evaluate the extent of LN dissection as well as the status of LN metastasis. Disease-free survival and dynamic risk stratification were compared for clinical outcomes.

Results

Presence of HT did not lower the risk of cervical LN metastasis (61.6% in patients with HT vs. 65.1% in patients without HT, p=0.292). Patients with HT had significantly larger numbers of removed LNs than patients without HT (11 vs. 8, respectively, p<0.001). Accordingly, metastatic LN ratio was smaller in patients with HT (p=0.002) which was independently associated with structural persistent/recurrent disease (hazard ratio [HR] 2.33, 95% confidence interval [CI] 1.30-4.16, p=0.004). HT itself was negatively associated with structural persistent/recurrent disease after adjustment for other clinicopathological factors (HR 0.39, 95% CI 0.18–0.87, p=0.020).

Conclusions

Coexistence of HT itself is an independent factor associated with favorable outcome in PTC patients, regardless of extent of LN dissection.

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